1. Field of the Invention
The present invention is directed generally to methods and systems related to processing and manipulating video images and more specifically to the analysis and preparation of consecutive images with respect to non-motion brightness changes to improve the estimation of dense motion fields in sequences of images, such as, e.g. video images, by optical flow computation.
2. Related Art
An example of motion estimation by optical flow computation is set forth in application Ser. No. 09/593,521, filed Jun. 14, 2000, entitled “System for the Estimation of Optical Flow,” invented by Siegfried Wonneberger, Max Griessl and Markus Wittkop. This application is hereby incorporated by reference. Motion estimation by optical flow computation between two consecutive images of a sequence is limited by the fact that the optical flow constraint does not allow for brightness changes between the two images when the brightness change is not due to motion. Therefore, brightness changes not caused by motion often lead to extremely incorrect motion fields and can even cause the breakdown of the motion estimation process. Simply identifying that a brightness change is not due to motion can be challenging, due to the variety of sources causing the brightness change, e.g. camera motion, object motion, innovations, occlusions, flashlights and scene-shifts. What is needed, then, is the ability to free the images from non-motion brightness changes before the motion is estimated.